Flow Like an Expert: Crafting Insightful Sankey Charts for Data Storytelling

In the realm of data visualization, Sankey diagrams have carved a niche for themselves as a highly efficient tool to visualize complex flows and distributions. Unlike traditional bar charts and line graphs, Sankey diagrams allow for the display of multiple data streams and their interconnections, making them particularly useful in industries such as environmental analysis, supply chain management, and social media analysis. Crafting an insightful Sankey chart requires a blend of understanding the narrative you want to convey and technical dexterity in data manipulation and visualization. Let’s delve into how to create captivating Sankey diagrams that tell compelling stories with data.

Understanding Sankey Diagrams

A Sankey diagram, named after Sankey’s 1898 study of steam engine efficiency, is a flow diagram that uses parallel bars to show the magnitude of multiple flow channels. It is a powerful method for visualizing large datasets that evolve over time or depict changes in a process. Each bar in the diagram represents a data flow, and the width of the bar indicates the flow rate, or the amount of data flowing through that channel.

Crafting an Insightful Sankey Chart

1. Identify the Narrative

Before you start creating a Sankey diagram, you need to identify the story you want to tell. Sankey diagrams are great for visualizing flows, such as energy flow in a system, consumer purchases across channels, or data migration processes. Clearly define your goal – is it to highlight an increase in sales from a specific channel, or to illustrate energy loss in a process? This will guide your data selection and arrangement.

2. Select your Data

Sankey diagrams are particularly effective with multi-modal data. They are often used to visualize how data flows from one source to another, and then further on to another destination. Look for datasets that exhibit this flow pattern. The data should be structured in a way that each row represents a flow and includes columns for source, destination, and the quantity (or volume) of the flow.

3. Sort Your Data

Arrange your data into a hierarchy. For example, in a supply chain context, you might categorize products as raw materials, intermediate goods, and final products before plotting them on the diagram. This hierarchical arrangement helps in creating a logical flow and makes the visualization easier to interpret.

4. Create the Sankey Diagram

There are several tools and libraries available for creating Sankey diagrams, including Tableau, Python (with matplotlib or Plotly), and R (with ggplot2 or gWidgets). Each provides its own set of tools and customization options, so choose the one that suits your skills and the requirements of your project.

Tableau: Offers an easy-to-use interface and support for multiple data sources.
Python: Offers a wealth of libraries such as Plotly for creating interactive diagrams, or matplotlib for simple diagrams.
R: Particularly well-suited for data scientists and researchers for its extensive visualization capabilities.

5. Format for Clarity

Labeling: Clearly label all inputs, outputs, and intermediate steps. Ensure font size is appropriately chosen for clarity.
Color: Use color to differentiate between different types of data flows or to highlight trends.
Width: Adjust the width of the bars to reflect the magnitude of the data flow.
Arrangement: Ensure that your arrangement of flows is logical and easy to follow, with minimal overlap for clarity.

Applications and Examples

Sankey diagrams are incredibly versatile and have applications in various fields. For instance:

Energy Analysis: Highlighting how much energy is lost at different stages of an energy conversion process.
Consumer Behavior: Visualizing how consumers arrive at and transact with a business, from organic search to social media ads.
Process Analysis: Identifying bottlenecks in manufacturing processes by visualizing the flow of materials and the time spent at each step.

Conclusion

Crafting insightful Sankey charts requires careful planning and technical expertise. By identifying the narrative you want to convey, selecting the right data, carefully sorting and arranging your data, and formatting your chart for clarity, you can create compelling diagrams that help in understanding complex data flows in your domain. Whether it’s for energy efficiency analysis, consumer journey mapping, or process optimization, Sankey diagrams offer a unique lens through which to view data, enhancing our ability to see the ‘flow’ of information.

SankeyMaster

SankeyMaster is your go-to tool for creating complex Sankey charts . Easily enter data and create Sankey charts that accurately reveal intricate data relationships.